Manufacture of semiconductor devices involves microfabrication by lithography using a resist composition. Microfabrication is a processing technique that includes forming a thin film of a photoresist composition on a semiconductor substrate such as a silicon wafer, irradiating the thin film with active light such as ultraviolet light through a mask pattern having a device pattern drawn thereon, developing the pattern, and etching the substrate using the resulting photoresist pattern as a protective film, thereby forming fine irregularities corresponding to the pattern on the substrate surface. As semiconductor devices have recently become further integrated, the active light used has also become shorter from an i-line (wavelength 365 nm) and a KrF excimer laser (wavelength 248 nm) to an ArF excimer laser (wavelength 193 nm). At present, lithography using EUV (abbreviation of extreme ultraviolet, wavelength 13.5 nm) exposure, which is an advanced microfabrication technology, is under study. Unfortunately, lithography using EUV exposure has not yet been put to practical use (mass production) for reasons such as a delay in the development of a high-power EUV light source.
Thus, various techniques have been studied to produce a finer pattern after using a conventional method for forming a resist pattern. A practical method among them is one in which a resist pattern formed within a range such that it can be stably obtained by a conventional method is covered with a composition for forming a fine pattern, and the resist pattern is expanded to reduce the diameter of the hole pattern (see Patent Documents 1 to 5).